Water electrolysis simply put is the decomposition of water into hydrogen (H2) and oxygen (O2) by passing an electrical current through it.
Over the past decade plus, many improvements have been made to the electrolyzer cell used for the electrolysis process; from the glass jars that dangled the plate assemblies in liquid to heavy plastic pipes and now more notably, thick polymer plates sandwiching together stainless steel and sealing materials to form a solid mass or “Brick” type device but, very little has been done to improve the electric control of the process.
Inherent problems with direct current (D.C.) water electrolysis are well known. One involves the need to use an electrolyte (catalyst) to improve electrical conduction. Specifically, as the electrolyzed water begins to conduct and draws current this causes heat to be produced. As the heat rises, so does the conduction. This thermal conduction cycle continues until thermal “runaway” occurs at which point the electrolysis cell looks like a dead short to the power supply—drawing enormous currents until damaging the power supply.
Another major problem is power consumption. Large amounts of power are required to sustain D.C. water electrolysis as seen above and because D.C. is constant, 100% of the power supplied is consumed by the device.
Recently, pulse-width modulators or PWM's as they are known have been used by some in an attempt to control the operating state of the elctrolyzer. Unfortunately, these “dumb” devices cannot tell how well they work in the circuit so a lot of “tweaking” is necessary to keep these systems “in tune”.
PWM controller technology was commercially developed in the 1970's as a means of A.C. electric motor control. Such electric motors are inductive devices where as an electrolytic cell is more a resistive circuit with capacitive attributes. PWM's work by switching the supply current on and off very fast at varying rates like 120 Hz in a lamp dimmer to 15-20 Khz in a computer power supply. By providing full power for part of the time less power is consumed.
Another method of mitigating the thermal (current) runaway is to monitor the temperature. Once it exceeds the acceptable level, the device is switched off to let it cool down, like the thermostat in your house. The problem is that when the device is switched off no gas is produced. Many other means of “open loop” control have been attempted in the past but none have produced the desired control over the electrolytic cell.
This document describes a novel and effective approach that utilizes D.C. servo closed loop control. A servomechanism or servo is a device used to provide control of a desired operation through the use of continuous feedback. The use of servo technology is not obvious in this application because most all servo applications deal with control of motion; motor control for speed/direction, or linear application for control of cylinders or slides. The widely recognized application is in robotic application where machine motions are controlled using three dimensional algorithms to move the robot hand to a precise location in a space (work frame). By applying D.C. servo closed loop control to an electrolysis cell a more precise control of the process is attained.